I'm a Wildland firefighter and can wear my Fits socks for 5 days in a row. More specifically I don't take them off once for five days. I sleep in them and sweat in them for 16 hrs a day while standing on hot ambers and carrying 50 lbs of gear, while wearing Whites Smokejumper boots! No smells, no blisters, no foot rot, simply amazing. Also I've tried smartwool, thorlo, and Patagonia brands. None compared to Fits comfort, durability, breath ability, insulation. Just try a pair on and you'll understand the comfort immediately.